1. Field of the Invention
The present invention relates to a bracket structure for increasing the load-carrying capacity and reinforcing the strength of a concrete structure and enabling easy construction, which solves the problems wherein, if an obstacle is present on the surface of concrete structure or an anchor bolt is directly subjected to the resistance force of a steel plate when the steel plate applying stress to the concrete structure is integrally secured to the bottom of the concrete structure using the anchor bolt, the steel plate as well as the anchor bolt is deformed, so that pre-stressing effect is weakened, and it is difficult to maintain permissible tolerance when installing the anchor bolt and the steel plate, because of the strain of the anchor bolt, and thereby the detail of the construction work is inaccurate and the installation of the steel plate to the concrete structure is not easy, and which uses an affixing bracket including a holding member which is connected to the bottom of a concrete structure using an anchor bolt, and a support member which is connected to a pre-stressing steel plate applying stress to the concrete structure connected to the holding member, thus making it easy to install the pre-stressing steel plate regardless of the condition of the bottom surface of the concrete structure or tolerance when installing the anchor bolt and the steel plate, and in which the support member of the affixing bracket forms a channel under the concrete structure to enlarge an area, thus increasing the moment of inertia of area of the concrete structure.
2. Description of the Related Art
Generally, the concrete structure is comprised of a beam of a building, a slab or a concrete girder of a bridge, and serves to bear the load of the building or bridge.
When a dead load (fixed load) or live load is applied to the concrete structure, the upper surface of the concrete structure CC is subjected to compression strain or stress.
In contrast, the bottom surface of the concrete structure CC is subjected to tension strain or stress.
However, in terms of the characteristics of the material of the concrete structure, it has high resistance to compression, but has low resistance to tension.
In order to overcome the weakness, a steel plate or a steel member is provided on the bottom surface of the concrete structure to apply stress thereto, thus increasing a load bearing capacity and strength of a concrete structure which has been installed or is being installed.
Thus, as shown in FIG. 1, in order to install a steel member or a pre-stressing steel plate 20 to a concrete structure CC, anchor bolts 1 are put in both ends of the bottom surface of the structure CC.
Further, a fastening hole is formed in each end of the pre-stressing steel plate 20 to engage an associated anchor bolt 1. After the anchor bolt 1 is inserted into the fastening hole of the pre-stressing steel plate 20, a nut 5 is screwed onto the anchor bolt 1, thus integrally coupling the concrete structure CC with the pre-stressing steel plate 20.
Moreover, an additional member such as a friction plate 7 is interposed between the concrete structure CC and the pre-stressing steel plate 20, thus realizing the smooth behavior of the concrete structure CC and the pre-stressing steel plate 20.
However, as in the prior art, when the pre-stressing steel plate 20 is directly secured to and integrated with the concrete structure CC, the following problems may occur.
That is, when a protrusion or an uneven obstacle is present on the surface of the conventional concrete structure CC, it is difficult to directly fix the pre-stressing steel plate 20 to the surface of the concrete structure CC, so that constructability is poor.
Further, since the anchor bolts 1 are directly subjected to the resistance force of the pre-stressing steel plate 20 against the compression strain or stress engaged on the bottom surface of the concrete structure CC, the pre-stressing steel plate 20 as well as the anchor bolts 1 is deformed, and the pre-stressing effect of the steel plate 20 is weakened.
Furthermore, because of the strain of the anchor bolts 1, it is difficult to maintain tolerance within a permissible range when installing the anchor bolts 1 and the pre-stressing steel plate 20, so that the detail of the construction work is inaccurate.
Further, it is not easy to install the pre-stressing steel plate 20 to the anchor bolts, so that constructability is poor.